System of control for electric motors.



B. G. LAMME. SYSTEM OF CONTROL FOR ELECTRIC MOTORS.

ARPLIGATION FILED APR.5, 1907.

Patented July 19,1910.

2 SHEETS-SHEET 1.

B. G. LAMME.

SYSTEM OF 0011111101, FOR ELECTRIC MOTORS.

APPLICATION FILED APR. 5, 1907. 964,794. Patented July 19,1910.

2 SHEETS-SHEET 2.

INVENTOR WITNESSES: 5,5451% ATTORNEY In: "all!!! rz'rtxs cu, WASHINGTON,01 c.

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BENJAMIN G. LAMME, OF I?ITTSBURG, PENNSYLVANIA, ASSIGNOR TO\IVES'lINGtHOU'SE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION 013PENNSYLVANIA.

SYSTEM OF CONTROL FOR ELECTRIC liLiOTORS.

Specification of Letters Patent.

Patented July 19, 1910.

Original application filed. May 3, 1904, Serial No. 206,18 l. Dividedand this application filed April 5, 1907. Serial No. 366,564,

To all whom "it may concern:

Be it known that l BENJAMIN G. LAMME, a citizen of the United States,and a resident of Pittsburg, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in Systems ofControl for Electric Motors, of which the following is a specification,this application being a division of my application, Serial No.206,184L, filed May 3, 1904.

My invention relates to systems of control. for electric motors, andparticularly to systems for controlling meters of the commutator typethat are adapted to operate on either alternating or direct current.

The object oi the invention is to provide means for so controlling thecircuits of motors of the character indi rated that they may be operatedeconomically and elliciently on either alternating or direct current.

It the proper alterations are made in the design and construction ofelectric motors having commutator-s and which have ordi narily beenoperated by means of direct current energy, such motors may also beoperated efiiciently and satisfactorily by means of alternating currentenergy, and in many cases it has become quite desirable to so constructthe motors and arrange their connections with the controlling devicesthat they may be operated by means of either alternating or directcurrent energy.

Four motors are ordinarily employed on a car when the amount of powerrequired for its operation is large, and it has been found mostexpedient to construct such motors for normal operation on 250 volts,two motors being connected in series between five hundred volt mains.

In certain cases, the controlling apparatus may be exactly the same,whether operating on alternating or direct current, and it is evidentthat a series-parallel method of con trol may be employed; that is, themotors may be connected all in series for starting and low speed runningconditions and in series-parallel relation to each other for the higherspeeds. One disadvantage, however, of operating alternating currentmotors by means of this series-parallel method of control, as usuallypracticed, lies in the fact that each two hundred and fifty volt motorhas only one hundred and twenty-five volts applied to its terminals,when required to give full load torque at practically zero speed.

If a series-parallel method of operation is used. when operating onalternating currents, it becomes necessary to pass into the parallelposition of the controller in order to obtain a higher torque or toattain a higher speed, and therefore, with this arrangement, there is nogain in operating the motors by means of the series-parallel method ofcontrol. In starting, practically all the drop in voltage in the motors.occurs in the field magnet windings, so that if these windings areconnected in seriesparallel or in parallel relation to each other andthe armature windings are connected in series, the voltage absorbed bythe field magnet windings will be reduced when starting and somebenefitis derived from the series con nection of the armatures. In thismanner the ratio of the armature strength to the field strength isincreased, which is an economical 7 5 and desirable condition forstarting. is this ratio is increased, greater armature current isrequired for a given torque than is required when the field magnetwindings are connected all in. series, but the current is less than isrequired ii it is necessary to pass to a seriesparallel connection ofthe motors in order to obtain the desired starting torque. Thisarrangement, therefore, provides economical starting conditions and alsopermits of running at low speeds with the armatures connected all inseries. It has also been found desirable in practice to provide meansfor al tering the ratio of field ampere turns to arm ature ampere turnswhen changing from one character ct energy to the other so that theratio in ay be greater when operating by direct current than whenoperating by alternating current. In Patent No. 794,362, granted toWestinghouse Electric & Manutact-tiring Company, upon an applicationfiled by me, is claimed both generically and specifically a means forellecting this result. According to my present invention, the desiredalteration in the ratio of the ampere turns is eltected by adjusting thecircuit re lations of the field magnet and armature windings of themotors.

My invention is illustrated in the accompanying drawings, in whichFigure 1 is a diagrammatic view of a system comprising suitablecontrolling devices for the motors. Figs. 2, 3, d and 5 are diagramsillustrating the conditions of the circuits corresponding to the variouspositions of the controller shown in Fig. 1. Fig. 6 is a diagrammaticview of another system comprising suitable controlling apparatus for themotors. Figs. 7, 8, 9 and 10 are diagrams illustrating the conditions ofthe circuits corresponding to the various positions of the controllershown in Fig. 6. Figs. 11 and 12 are diagrams illustrating modificationsof the methods illustrated in the preceding figures.

deferring now to Fig. 1, it is seen that alternating current energy issupplied from a suitable source 1 to line conductors 2 and 3 and directcurrent energ 1 from a suitable source at to line conductors 5 and 6.One terminal of a main transformer winding 7 is connected to lineconductor 3 and the other terminal to terminal 8 of a switch 9 providedfor the purpose of changing the kind of energy supplied to the pairs ofmotors 11 and 12 from alternating to direct current. One terminal of asecondary winding 13 of a series transformer H, having a primary winding15, is connected with a point 16 in the winding 7 that is intermediatethe terminals thereof, and the other terminal is connected to terminal17 of the switch 9 and to terminal 18 of a reversing switch 19. Theterminals of the primary winding 15 are connected respectively toterminals 20 of the reversing switch 19, and terminal 21 is connected toan arm 22 which is adapted to engage respectively with contact terminals22, which are connected to suitable points in the winding 7. Thisportion of the apparatus provides suitable means for varying the voltagesupplied to the motors when operating on alternating current, the speedbeing varied by properly manipulating the reversing switch 19 and thearm 22.

Means for varying the speed of the motors when operating on directcurrent may be a suitable rheostat 23 comprising a subdivided resistanceelement 2 l connected to the line conductor 5 and a suitable arm 25,which is adapted to make contact with terminals 26 connected at variouspoints to the resistance 2st. The arm 25 is connected to terminal 27 ofthe switch 9, and terminals 28, 29 and 30 of the switch 9 are connectedrespectively to line conductors 6 and 2 and contact finger 31 ofcontroller 32. Terminal 29 of the switch 9 is also connected to contactfinger 33 of the controller 32. If

switch 9 is in the position shown in full lines in Fig. 1, alternatingcurrent energy is supplied to the controller 32, but if the switch is inposition to connect terminals 29 and 30 respectively with terminals 28and 27, direct current is supplied to the controller 32. This switch maybe operated manually or it may be operated automatically by suitabledevices when a change is made from alternating current to direct currentor vice versa; that is, the system may be so organized that a change ofsupply of energy from alternating to direct current will operate theswitch 9 automatically without the attention of the operator.

The controller 32 represents a suitable device for adjusting theconnections of the field and armature windings with reference to eachother, the conducting strips or ments to the left of the contact fingersbeing provided for the purpose of adjusting the connections of the fieldmagnet and armature windings when operating on alternating current andthe strips or segments shown to the right of the contact fingers 31being for the purpose of adjusting the connections of the field magnetand armature windings when operating on direct current, the said stripsto the right and to the left being adapted to engage properly with thecontact fingers.

If it is desired to operate the motors by means of alternating currentenergy, the switch 9 should occupy the position shown in full lines andthe controller should be moved to the position a, in which position thefield magnet windings are connected two in series and two in paralleland the armature windings all in series, as shown in Fig. 2, theseconnections being for starting conditions and lower speeds. The speed ofthe motors may then be varied by varying the voltage supplied thereto bymeans of the reversing switch 19 and the arm 22, up to approximatelyhalf speed. In the position I) of the controller, the field magnetwindings are still connected in the series-parallel relation to eachother, but the relations of the armature windings are changed from theseries connection to a series-parallel connection, as shown in Fig. 3,and the motors may then be brought up to full speed.

If it is desired to operate the motors by means of direct currentenergy, the switch 9 is thrown so as to connect the terminals 29 and 30respectively with the terminals 28 and 27 and the controller is moved tothe position 0 for starting conditions of the motors, and the fieldmagnet and armature windings are then connected all in series, asindicated in Fig. 1. The speed of the motors may then be varied by theoperation of the arm 25 of the rheostat 23. The motors may be connectedin the ordinary seriesparallel relation to each other, as indicated inFig. 5, by the movement of the controller to position (Z and they maythen be brought to full running speed by gradually cutting theresistance 2 f out of the circuit.

The controller in the system shown in Fig. 6 is adapted to connect thefield magnet and armature windings in slightly different relations toeach other from those shown in Figs. 2, 3, 4 and 5. In this figure,terminal 29 ot the switch 9 and contact finger 33 are respectivelyconnected to terminals 85 and 36 of a switch 37 provided for the purposeof connecting the armature windings of the motors in series or inseries-parallel relations to each other, as desired. It the switch 37 isin the position shown, current will iiow from the finger 33 to switchterminal 36, and thence in two parallel paths to conductor 38, one pathbeing through blade 39, terminal 40, cross-conductor 41, terminal 42 andarmatures 12 and the other path being through armatures 11, switchterminal 48, blade ell and terminal. 35. If the switch 37 is in itsother closed position, the circuit from finger 33 is through terminal36, arma tures 11, terminal 43, blade 14i, terminal a2 and armature 12.It will therefore be seen that when the switch 87 is in the positionshown the armatures will be connected in series-parallel relation, andwhen it is in its other closed position the armatures will be connectedin series relation.

If it is desired to operate the motors by means of alternating currentenergy, the switch 9 will occupy the position shown, the switch 37 itsclosed position opposite that shown, and the controller 32 will be movedto position a, the field magnet windings of the motors being thenconnected in parallel and the armature windings in series, as shown inFig. 7. The speed of the motors may then be varied, up to approximatelyhalf speed, by the operation of the reversing switch 19 and the arm 22.In order to bring the motors up to full speed, the controller will bemoved to position b, the switch 37 to the position shown, and thevoltage varied as before, the field magnet windings and also thearmature windings being then connected in series-parallel relation toeach other, as shown in Fig. 8.

The operation of the motors by means of direct current energy may beexactly the same as that described in connection with Fig. 1, theconnections of the field magnet and armature windings being shown inFigs. 9 and 10. In order to secure these connections of the motors, itis necessary to turn the movable member of the switch 9 into engagementwith the contact terminals 27 and 28, the movable member of the switch37 to the position opposite that shown, and the controller to theposition 0 for starting conditions, such as are shown in Fig. 9; and theswitch 37 to the position shown, and the controller to position (Z forrunning con ditions such as are shown in Fig. 10. It

may be desirable, however, to connect the field magnet and armaturewindings for starting and running conditions of the motors as shownrespectively by Figs. 11 and 12, it: being necessary, in order to obtainthese connections, to place the controller in the position (Z and tothrow the switch 37 into the position opposite that shown for startingconditions, such as those shown in Fig. 11, and then to throw the switchto the position shown for the running conditions, such as are shown inFig. 12.

lVhile I have shown and described suitable devices for controlling thecircuits of the motors and the voltages applied thereto, I do not limitmyself to such specific means, since it is evident that many othersuitable arrangements of the controlling devices may be employed and itis possible to combine all of the devices into a simple and compactpiece of apparatus having one or more controller drums for adjusting theconnections of the circuits. Other specific means may be devised forconnecting the armature and field magnetwindings of motors in suchrelations as to alter the ratios of the ampere turns of those windingswhen changing from one character of energy to another or when effectingchanges in the speed. of operation, and I desire my invention to beconstrued broadly to cover all such means, though they are not herespecifically shown and described.

I claim as my invention:

1. The combination with a plurality of electric motors having fieldmagnet and armature windings, of means for connecting the motorsalternately to a source of alternating current and to a source of directcurrent, and means for adjusting the connections of said windings toobtain a comparatively small number of field ampere turns when operatingon alternating current and a larger number when operating on directcurrent.

2. The combination with a plurality of electric motors adapted tooperate on either alternating or direct current, of means for adjustingthe circuit relations of the field windings to obtain a comparativelysmall number of field ampere turns when operating on alternating currentand a larger number when operating on direct current.

8. The combination with a plurality of electric motors adapted tooperate on either alternating or direct current, of means for adjustingthe circuit relations of the windings of said motors to vary the ratioof the ampere turns in the field magnet windings to those in thearmature windings when changing from one character of energy to theother.

4. The combination with a plurality of electric motors adapted tooperate on either alternating or direct current, and voltage adjustmentdevices corresponding to each character of current, of means foradjusting the circuit relations of the field magnet windings to obtain acomparatively small number of field ampere turns when operatlowerspeeds, and a larger number or field ampere turns when operating ondirect current and at higher speeds 5. The combination with a pluralityof electric motors having series-connected field magnet and armaturewindings, of means for adjusting the circuit relations of the fieldmagnet windings to obtain a comp-arr.- tively small number of fieldampere turns for each of a plurality of lower speeds and a larger numberfor each of a plurality or" higher speeds.

(3. The combination with a plurality of electric motors having fieldmagnet and armature windings, or means for adjusting the circuitrelations of said windings so that only a portion of the total currentsupplied to the armature windings traverses each of the field magnetwindings while the total current traverses each of the armature windingsfor each of a plurality of lower speeds.

T. The combination with a electric motors having field magnet andarmature windings, of means for adjusting the the field magnet windingswhile the total i current traverses each of the armature wmdl iugs foreach of a plurality of lower speeds and tor connecting the armaturewindings so that only a portion of the total current traverses each ofthem for each of a plurality of higher speeds.

8. The combination with a plurality of electric motors adapted tooperate on either alternating or direct currenh of means for adjustingthe circuit relations of the windings of said motors so that whenoperating on alternating current only a portion of the total amount ofcurrent supplied to the motors traverses each of the field magnetwindings while the total amount traverses the armature windings t'or thelower speeds, and so that only a portion of the total amount of currenttraverses each of the armature windings tor the higher speeds and for soarranging on alternating current and also fort ing the circuit relationsof the windings that, when operating on direct current, the total amountof current traverses both the field magnet and armature windings "forthe lower speeds and only a portion of the total amount traverses eachof the windings for the higher speeds.

9. The combination with a plurality of electric motors haying fieldmagnet and armature windings, or means for connecting the field magnetwindings in parallel relation to each other and the armature windings inseries relation to each other for lower 1 alternating or direct current,of means for j connecting the field magnet windings of said motors inparallel relation to each other and 1' the armature windings in seriesrelation for plurality of i the lower speeds and the armature windingsin series-parallel relation to each other for the higher speeds whenoperating on alter ating current. and for connecting the motors inseries for lower speeds and in series parallel for higher speeds whenoperating on direct current.

11. In combination, a plurality of series motors adapted for operationon either alternating or direct current, and a control system arrangedto connect said motors to a source of alternating current with the fieldconnections of the motors arranged to give a comparatively small numberof ampere turns and to a direct current source, two in series, with thefield connections modified to a comparatively large number of ampereturns In testimony whereof, I have hereunto subscribed my name this 29thday of March, 1907.

BENJ. Gr. LAUME.

lYitnesses:

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